1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
|
/*
* linux/fs/nfs/symlink.c
*
* Copyright (C) 1992 Rick Sladkey
*
* Optimization changes Copyright (C) 1994 Florian La Roche
*
* Jun 7 1999, cache symlink lookups in the page cache. -DaveM
*
* nfs symlink handling code
*/
#define NFS_NEED_XDR_TYPES
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfs_fs.h>
#include <linux/nfs.h>
#include <linux/pagemap.h>
#include <linux/stat.h>
#include <linux/mm.h>
#include <linux/malloc.h>
#include <linux/string.h>
/* Symlink caching in the page cache is even more simplistic
* and straight-forward than readdir caching.
*/
static int nfs_symlink_filler(struct dentry *dentry, struct page *page)
{
struct nfs_readlinkargs rl_args;
kmap(page);
/* We place the length at the beginning of the page,
* in host byte order, followed by the string. The
* XDR response verification will NULL terminate it.
*/
rl_args.fh = NFS_FH(dentry);
rl_args.buffer = (const void *)page_address(page);
if (rpc_call(NFS_CLIENT(dentry->d_inode), NFSPROC_READLINK,
&rl_args, NULL, 0) < 0)
goto error;
SetPageUptodate(page);
kunmap(page);
UnlockPage(page);
return 0;
error:
SetPageError(page);
kunmap(page);
UnlockPage(page);
return -EIO;
}
static char *nfs_getlink(struct dentry *dentry, struct page **ppage)
{
struct inode *inode = dentry->d_inode;
struct page *page;
u32 *p;
/* Caller revalidated the directory inode already. */
page = read_cache_page(&inode->i_data, 0,
(filler_t *)nfs_symlink_filler, dentry);
if (IS_ERR(page))
goto read_failed;
if (!Page_Uptodate(page))
goto getlink_read_error;
*ppage = page;
p = (u32 *) kmap(page);
return (char*)(p+1);
getlink_read_error:
page_cache_release(page);
return ERR_PTR(-EIO);
read_failed:
return (char*)page;
}
static int nfs_readlink(struct dentry *dentry, char *buffer, int buflen)
{
struct page *page = NULL;
int res = vfs_readlink(dentry,buffer,buflen,nfs_getlink(dentry,&page));
if (page) {
kunmap(page);
page_cache_release(page);
}
return res;
}
static struct dentry *
nfs_follow_link(struct dentry *dentry, struct dentry *base, unsigned int follow)
{
struct page *page = NULL;
struct dentry *res = vfs_follow_link(dentry, base, follow,
nfs_getlink(dentry, &page));
if (page) {
kunmap(page);
page_cache_release(page);
}
return res;
}
/*
* symlinks can't do much...
*/
struct inode_operations nfs_symlink_inode_operations = {
readlink: nfs_readlink,
follow_link: nfs_follow_link,
};
|
